May 7th: Mars Impactor & Neighboring World

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Podcaster: Dr. Al Grauer
travelers-in-the-nightTitle:
Travelers in the Night Digest: Eps.285 & 286: Mars Impactor & Neighboring World

Organization: Travelers in The Night

Link : Travelers in the Night ; @Nmcanopus

Description: Today’s 2 topics:

  • Youngmin JeongAhn and Dr. Renu Malhotra of the Univ. of Arizona’s LPL have published their paper on Mars impactors. Mars has a 3 times greater chance of being hit by a half mile-wide impactor when it’s farthest from the Sun in its slightly elliptical orbit.
    https://arxiv.org/pdf/1701.03096.pdf
  • ESO astronomers have discovered a planet orbiting Proxima Centauri. Proxima B is about 1.3 Earth masses and has an 11 day orbit around its red dwarf star.

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Bio: Dr. Al Grauer is currently an observing member of the Catalina Sky Survey Team at the University of Arizona.  This group has discovered nearly half of the Earth approaching objects known to exist. He received a PhD in Physics in 1971 and has been an observational Astronomer for 43 years. He retired as a University Professor after 39 years of interacting with students. He has conducted research projects using telescopes in Arizona, Chile, Australia, Hawaii, Louisiana, and Georgia with funding from NSF and NASA.

He is noted as Co-discoverer of comet P/2010 TO20 Linear-Grauer, Discoverer of comet C/2009 U5 Grauer and has asteroid 18871 Grauer named for him.

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Transcript:
285 -Mars Impactor
In 2015 the Earth was struck by at least 43 meteoroids which created bright fireballs. Their arrival does not seem to be correlated with the position of the Earth in it’s orbit about the Sun.

Overall a given piece of ground on Mars is several times more likely to be hit by a space rock than is a similar sized area on Earth. Recently, Youngmin JeongAhn and Dr. Renu Malhotra of the University of Arizona’s Lunar and Planetary Laboratory published a paper reporting their analysis of the current impact rate of small objects onto Mars. The red planet’s very elliptical orbit is aligned with the known Mars crossing asteroids and carries it nearer the main asteroid belt when it is farthest from the Sun. JeongAhn and Malhotra have determined that these factors make the chance of Mars being hit by a half mile sized asteroid to be three times greater when it is it’s furtherest from the Sun than it is at the other extreme of it’s orbit. They also find that the impact rate of smaller 3 foot diameter objects, which cause fireballs on Earth, is likely to change between 3 to 15 times as Mars orbits the Sun. There could be as few as 15 or as many as 186 new impact craters every Martian year. This estimate will be refined as the Mars Reconnaissance Orbiter continues to discover fresh craters on the surface of the red planet.

All of this is causing me to wonder if in the future the Martian tourist industry will bring visitors to view super meteor storms which occur each year when Mars is furtherest from the Sun.

286 -Neighboring World
Astronomers at the European Southern Observatory in Chile have discovered a rocky Earth like planet orbiting Proxima Centauri, the star nearest to our Sun. The planet named Proxima b is about 1.3 times more massive than Earth, orbits it’s dim red star every 11 days, and may always keep the same side towards it’s sun. Attention grabbing is the fact that Proxima b is at the right distance from it’s sun to allow for liquid water on it’s surface.

Just as is the case with the Earth, the key to Proxima b’s potential as an abode for life lies in the density and composition of it’s atmosphere if it has one. A complication is that Proxima b receives 60 times more high energy radiation than Earth.

Current evidence does not allow scientists to determine if Proxima b has lost its atmosphere and is thus like our moon or if it has been able to hold on to most of it’s atmosphere and thus currently has liquid water on its surface. To probe this mystery scientists from Spain, Belgium, France, Germany, UK, and the USA analyzed possible atmospheres and climates on Proxima b. Their results suggests that liquid water may only be present on the sunniest portions of the planet either on the side of the planet facing it’s star or in a temperate zone along its equator.

The next generation of super-sized telescopes will give astronomers the ability to measure the thickness and composition of Proxima b’s atmosphere and oceans if they exist. Proxima b is tantalizing place since the Physics of the Universe allows us study it from a far and perhaps even send a super light robotic probe to it in the not too distant future.

For Travelers in the Night this is Dr. Al Grauer.

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365 Days of Astronomy
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